Procedure for the preparation of high viscosity - high vi lubricating oils

ABSTRACT

A process for producing lubricating oils in order to obtain lubricating oils of enhanced viscosity index by hydrotreating various crude lubricating oil fractions separately and thereafter separately fractionating the hydrotreated materials.

United States Patent Henke et al. Oct. 9, 1973 [54] PROCEDURE FOR THE PREPARATION OF 3,579,435 5/1971 Olenzak et a1 208/59 HIGH VISCOSITY HIGH VI LUBRICATING 2,787,582 4/1957 Watkins et al 208/58 OILS 3,493,493 2/1970 Henke et a1. 208/264 3,649,518 3/1972 Watkins 208/59 [75] Inventors: Alfred M. Henke, Springdale; Harry 3,649,519 3/ 1972 Watkins 208/59 C. Stauffer, Cheswick, both of Pa.

[73] Assignee: Gulf Research & Development Primary ExaminerDelbert E. Gantz Company, Pittsburgh, Pa. Assistant Examiner--G. E. Schmitkons [22] Filed Oct 20 1971 Att0rneyMeyer Neishloss et a1.

[2]] Appl. N0.: 190,782

[57] ABSTRACT 2% 23 A process for producing lubricating oils in order to d g 208g80 obtain lubricating oils of enhanced viscosity index by 1 le 0 l hydrotreating various crude lubricating oil fractions separately and thereafter separately fractionating the [56] References cued hydrotreated materials.

UNITED STATES PATENTS 2,917,448 12/1959 Beuther et a1. 208/57 5 Claims, 2 Drawing Figures 48 FQACT/OA/ATOR /aqAcr oA Ame .52

FQACWOA ATOR REACTOR .56 22 1 FRACT/OA/ATOR 40 A? a L V 7 V .42

PROCEDURE FOR THE PREPARATION OF HIGH VlSCOSlTY HIGH VI LUBRICATING OILS Our invention relates to the production of lubricating oils by hydrotreating. More particularly, our invention relates to the production of lubricating oils by separately subjecting various crude lubricating oil fractions to hydrotreating and then separately fractionating the effluents.

It has previously been suggested in the art to subject hydrocarbon fractions boiling in the lubricating oil range to various treatments with hydrogen in order to provide lubricating oil base stocks meeting desired specifications, such as, for example, viscosity, viscosity index (Vl), pour point and acceptable contaminant levels. These hydrogen treatment techniques are designated by a variety of terms whose definitions tend to overlap depending upon the individual employing such terms. Regardless of the inadequacy of nomenclature in this area, these hydrogen treatment processes can be categorized into four different groups. We chose to term these categories as hydrocracking, hydrotreating, hydrogenation and hydrofinishing.

As employed herein the term hydrocracking is meant to describe an extremely severe hydrogen treatment, usually conducted at comparatively high temperatures and requiring the employment of a catalyst having substantial cracking activity, e.g., an activity index (Al) greater than 40 and generally greater than 60. This type of process is conducted to effect extensive and somewhat random severing of carbon to carbon bonds resulting in a substantial overall reduction in molecular weight and boiling point of treated material. Thus, for example, hydrocracking processes are generally employed to effect an extremely high conversion, e.g., 90 percent by volume, to materials boiling below the boiling range of the feed stock or below a designated boiling point. Usually a hydrocracking process is employed to produce a product boiling predominantly, if not completely, below about 600 to 650F. Most frequently this type of process is employed to convert higher boiling hydrocarbons into products boiling in the furnace oil and naphtha range. When applied in connection with lubricating oils, hydrocracking processes produce only a minor quantity of materials boiling in the lubricating oil range, i.e. 625 to 650F.+, to the extent that, at times, the production of a lubricating oil is merely incidental to the production of naphtha and furnace oil. l-lydrocracking is the most severe of the four types of processes mentioned above.

On the other end of the spectrum, hydrofinishing is an extremely mild hydrogen treatment process employing a catalyst having substantially no cracking activity. This process effects removal of contaminants such as color forming bodies and a reduction of minor quantities of sulfur, oxygen and nitrogen compounds, but effects substantially no saturation of unsaturated compounds such as aromatics. This process, of course, effects no cracking As a general rule, hydrofinishing is employed in lieu of the older techniques of acid and clay contacting.

The third type of hydrogen treatment process is hydrogenation" which, as employed herein, describes another comparatively mild process. Hydrogenation, although being comparatively mild, is more severe than hydrofinishing and generally effects saturation of unsaturated materials such as aromatics. A hydrogenation process is also capable of removing somewhat larger quantities of contaminants such as sulfur. A hydrogenation process is conducted with a catalyst having substantially no cracking activity and accordingly does not produce any significant reduction in boiling point of the material treated over and above that which might be effected from sulfur removal alone. Accordingly, therefore, a hydrogenation process is employed, albeit infrequently, in the area of lubricating oil production in order to effect saturation of aromatics and removal of sulfur from a charge stock already boiling within the lubricating oil range without the production of any lower boiling materials.

As distinguished from hydrocracking, hydrofinishing and hydrogenation, the term hydrotreating is employed herein to describe a processing technique significantly more severe than hydrogenation although substantially less severe than hydrocracking. The catalyst required in a hydrotreating process must possess cracking activity and generally possess a particular type of activity termed ring scission activity. The degree of cracking and ring scission activity is dependent upon feedstock and product desired. Thus, a hydrotreating process effects a substantial molecular rearrangement as compared to hydrogenation or hydrofinishing but does not effect the extensive and somewhat random breakdown of molecules effected in hydrocracking. Accordingly, this type of process effects substantially complete saturation of aromatics and the reactions are believed to follow the course of converting condensed aromatics to condensed naphthenes followed by selective cracking of the condensed naphthenes to form single ring alkylnaphthenes. Thus, polynuclear compounds are attacked and the rings are opened, while mononuclear cyclic compounds are not substantially affected. The alkyl side chains formed by opening the rings are not further reacted to sever the alkyl side chains. l-lydrotreating processes are also effective for the isomerization of paraffins. As with the less severe hydrogenation process and the more severe hydrocracking process hydrotreating is also effective to remove contaminants such as sulfur, nitrogen and oxygen. Thus, a hydrotreating process removes contaminants, reduces the quantity of aromatics and polynuclear cyclic compounds and increases the quantity of paraffins, thereby enhancing the quality of the material treated, reducing its iodine number and increasing its VI.

A hydrotreating process can also be identified by the fact that the particular combination of operating conditions and catalyst selected to accomplish the abovementioned results produces a product wherein there is a general decrease in Vl from the highest viscosity fraction to the lowest viscosity fraction of the lubricating oil. While at times the rate of decrease in VI with decreasing viscosity may be extremely slight or even appear to be non-existent among extremely high viscosity fractions, the rate of decrease in VI tends to become .greater as the viscosity of the lubricating oil fraction decreases. Usually, this decrease in VI with decreasing viscosity is particularly pronounced among the lighter lubricating oils having the lowest viscosities, such as, for example, materials whose viscosity is usually measured in Saybolt Universal Seconds (SUS) at F. Additionally, this phenomenon is evidenced quite drastically in hydrotreated lubricating oil products having viscosities of less than about 300 SUS at 100F. and obtained from distillate charge stocks. This is not to say,

however, that the decrease in VI with decreasing viscosity cannot be seen quite clearly in the hydrotreated products of residual stocks whose viscosities, at times, are more conveniently measured in SUS at 210F.

The particular operation involved in the process of 5 our invention is hydrotreating as distinguished from hydrofinishing, hydrogenation and hydrocracking. The material normally charged to a hydrotreating operation can be termed as crude lubricating oil stock and is generally obtained from crude petroleum by distillation so as to provide a material boiling at least above about 600F. and preferably above about 625 to 650F. Depending upon the crude petroleum from which the crude lubricating oil stock is obtained, such material may be subjected to a pretreatment such as solvent extraction prior to being charged to a hydrotreating operation. Within the overall boiling range of crude lubricating oils, we term materials boiling up to about 950 to l,O00F. as distillates or distillate crude lubricating oil stocks" while we term the portions boiling above about 950 to l,000F. residuals or residual crude lubricating oil stocks." In connection with residual crude lubricating ,oils, it may be desirable, depending upon the source of the crude, to subject such material to deasphalting such as, for example, propane deasphalting, prior to charging it to a hydrotreating process. The products from hydrotreating operations can be fractionated and blended with each other to produce desired lubricating oil products and in some instances, depending upon specific end uses of the lubricating oils, such materials can be subjected to finish operations, such as acid and clay contacting or the hydrofinishing treatment described previously.

In hydrotreating a wide boiling range crude lubricating oil the effluent from hydrotreating is usually fractionated so as to remove undesired light materials, such as, for example, furnace oil and lighter. The remaining lubricating oil boiling range materials can be referred to as a bulk product. Generally, the VI of the bulk product can be increased (within limits) by increasing the severity of the hydrotreating conditions. This increase in VI, however, is accompanied by an undesired decrease in viscosity of the bulk product. Similarly, this phenomenon is noticed in the individual lubricating oil product fractions when the bulk product is fractionated. Thus, if a comparison is made between the viscosity and VI for corresponding boiling range product fractions, it will be seen that usually the VI of each individual fraction evidences an increase with an increase in severity but that the viscosity of each of the product fractions generally shows a corresponding decrease.

We have discovered, however, that a product or products having an enhanced viscosity-VI relationship can be obtained if individual crude lubricating oil fractions rather than, for example, a bulk wide boiling crude lubricating oil, are separately subjected to hydrotreating and if each of the hydrotreated effluents is also separately subjected to fractionation. It must be pointed out that it is essential to the successful operation of our process that each of the hydrotreated fractions be separately fractionated for the removal therefrom of undesired lower boiling materials and that the separate hydrotreated effluents not be combined in a single fractionation operation. We have found that separate hydrotreating of various individual fractions, combining the hydrotreated effluents and then fractionating the combined effluents yields a bulk product and individual product fractions substantially no different from those obtained from hydrotreating a bulk wide boiling range crude lubricating oil.

The feed stock suitable for employment in our invention can be a wide boiling crude lubricating oil or two or more individualcrude lubricating oil fractions of substantiallydifferent boiling ranges. As will be understood, the wide boiling crude lubricating oil must be fractionated so as to obtain separate crude lubricating oil fractions of differing boiling ranges prior to charging such separate fractions to separate hydrotreating operations, while individual crude lubricating oil fractions obtained from different sources can be charged directly to their respective hydrotreating operations. While the process of our invention provides advantageous results when employing only two lubricating oil fractions of substantially different boiling ranges, we prefer to employ at least three separate crude lubricating oil fractions as feed stock. In one mode of operation, the separate lubricating oil fractions we employ as charge stocks correspond substantially to the product fractions desired.

Generally, an individual lubricating oil base stock fraction, i.e., the product of hydrotreating, and the corresponding individual crude lubricating oil fraction, i.e., the charge to hydrotreating, boil over a nominal range of about 100F. At times, the actual spread from initial boiling point (18?) to end point (EP) of the fraction may be somewhat greater or lesser than the nominal 100F. but the spread from 10 percentto percent point rarely exceeds F. and is usually well within the 100F. range, e.g., about 80F. A charge stock to the present invention, however, has been termed a wide boiling crude lubrication oil which is meant to define a crude lubricating oil boiling over a range of at least about 150 and frequently boiling over a range of at least 200F. Such a wide boiling crude lubricating oil will also have a spread between 10 percent point and 90 percent point of at least about F. and usually at least about 170F. In accordance with our invention, such stock is fractionated into at least two fractions and the fractions are then separately hydrotreated.

Similarly, when individual crude lubricating oil fractions obtained from different sources are to be employed as the charge stocks to the separate hydrotreating operations of our invention, the spectrum of boiling ranges of the several individual fractions encompass at least about F. and preferably about 200F. As will be understood, the greater the overall boiling range of either the wide boiling crude lubricating oil or of the individual crude lubricating oil fractions, the greater is the advantage to be obtained from our invention. Further, fractionation of the wide boiling crude lubricating oil into a multiplicity of fractions of the nominal 100F. boiling range or the employment of a multiplicity of individual fractions of the nominal 100F. boiling range also provides an enhancement in results obtainable in accordance with our invention.

If a wide boiling crude lubricating oil contains residual components, the crude lubricating oil can be fractionated so as to separate a single residual fraction for separate hydrotreating even though the boiling range of such residual fraction is significantly greater than 100F. Similarly, if an individual residual crude lubricating oil fraction is obtained from a source separate from that of the other crude lubricating oil fractions to be treated, it is not necessary to effect further fractionation of such individual residual crude lubricating oil fraction prior to subjecting it to separate hydrotreatment.

The catalyst employed in the process of our invention is a dual functional catalyst comprised of a hydrogenating component on a cracking carrier. Suitable catalysts include metalliferous hydrogenating components selected from the group consisting of Group VI and Group VIII metals, their oxides and sulfides supported on a carrier having cracking activity. Suitable cracking carriers include those having an Activity Index of at least about 15. Carriers having an Activity Index which is comparatively high, e.g., greater than about 60, are also quite satisfactory. Conversely, we have found that in some employments carriers having an Activity Index of less than about 20 and even less than about 18 can be utilized satisfactorily. Illustrative of these catalysts are those containing a plurality of hydrogenating components such as combinations of nickel, cobalt and molybdenum; nickel and tungsten; cobalt and molybdenum, etc. supported on refractory metal oxide carriers. Suitable carriers can be comprised of a single oxide or a plurality of such oxides, e.g., alumina, silica-alumina, silica-magnesia, silica-zirconia, silica-aluminamagnesia, etc. We have found a catalyst comprised of nickel and tungsten hydrogenating components supported on a silica-alumina carrier to be quite satisfactory. Additionally, all of these catalysts can be promoted by the addition thereto of a small quantity of halogen in the range from about 0.1 to about percent by weight based on the total catalyst, and preferably from about 1 to about 4 percent by weight based upon the total catalyst. We prefer to employ a catalyst containing from about I to 3 percent by weight of fluorine based on the total catalyst.

The operating conditions employed generally in the hydrotreating operations in accordance with our invention include a temperature in the range from about 600 to about 900F., preferably from about 700 to about 850F. and particularly from about 725 to about 825F.; a hydrogen partial pressure in the range from about 2,000 to about 10,000 PSI and preferably in the range from about 2,500 to about 5,000 PSI; a liquid hourly space velocity (LHSV) in the range from about 0.l to about 10 and preferably from about 0.5 to about 5.0 volumes of crude lubricating oil feed stock per volume of catalyst per hour; and a hydrogen feed rate in the range from about 2,000 to about 10,000 standard cubic feet per barrel (SCF/B) and preferably in the range from about 3,000 to about 6,000 SCF/B. It is not necessary to employ pure hydrogen gas in the hydrotreating operations but it is desirable to maintain a hydrogen purity of at least about 50 percent by volume. Thus, impure hydrogen streams of the type generally found in a refinery, such as, for example, reformer offgas, containing from about 70 to about 90 percent by volume hydrogen are quite satisfactory. The operating conditions employed in the separate hydrotreating operations of our process need not vary in severity for the different fractions and all fractions can be treated under the same severity or the same set of conditions.

Further, we prefer to employ operating conditions in our hydrotreating operations selected from the abovedescribed ranges so as to obtain a yield of at least 50 percent by volume based upon total reactor charge stock of 625F.+ material. Accordingly, the operating conditions are selected so that at reactor outlet conditions the 625F.+ material comprises at least 22 mol percent of the product which is normally liquid at 60F. and one atmosphere. Furthermore, operating conditions are selected so that the actual hydrogen consumption (measured as standard cubic feet per barrel of fresh feed) is less than the product of 30 multiplied by volume percent (measured at 60F. and one atmosphere) of 625F.+ material in the total C reactor effluent.

In conducting the separate fractionations in accordance with our invention, it is essential that the hydrotreated lubricating base oil product be separated from the components in each effluent boiling below the lubricating oil boiling range, e.g., furnace oil and lighter material boiling below about 650F. Additionally, we prefer to conduct the separate fractionations of our invention so as to separate from the desired lubricating base oil fraction at least about 10 percent by volume based upon lubricating oil boiling range effluent of the lightest lubricating oil boiling range materials. Generally, however, the amount of the highest lubricating oil boiling range materials in the hydrotreated effluent separated from the desired lubricating base oil product does not exceed about 30 percent by volume based upon the total lubricating oil boiling range materials in the hydrotreated effluent.

In order to describe our invention in greater detail, reference is made to the attached drawings wherein FIGS. 1 and 2 are flow schemes showing different methods of operating the process of our invention.

In FIG. 1, a residual-containing wide boiling crude lubricating oil boiling above about 0F. is introduced by means of line 10 into fractionator 12 operated so as to separate the crude lubricating oil into an overhead fraction boiling from about 650 to 850F., an intermediate fraction boiling from about 850 to about 1,000F., and a bottoms fraction (containing the residual components) boiling above about 1,000F. These fractions are removed from fractionator 12 by means of lines l4, l6 and 18, respectively. The residual fraction of line 18 is subjected to solvent deasphalting by conventional means, such as, for example, propane deasphalting. The deasphalting unit is schematically represented by block 20 showing solvent being introduced via line 22, solvent being removed via line 24 and asphaltic materials being removed via line 26. Deasphalted oil is removed from deasphalting unit 20 by means of line 28. The 650 to 850F. fraction of line 14, the 850 to 1,000F. fraction of line 16 and the deasphalted oil of line 28 are then introduced into hydrotreating reactors 30, 32 and 34, respectively, wherein these fractions are separately subjected to hydrotreat- Each of the reactors 30, 32 and 34 contains a fixed bed of a suitable catalyst, such as, for example, nickeltungsten-fluorine on a silica alumina carrier having an AI of about 75. In each of the reactors, the respective fraction is contacted with the catalyst in the presence of hydrogen under hydrotreating conditions of temperature, pressure and space velocity. The particular operating conditions employed in the three reactors 30, 32 and 34 can be the same or can differ in their severity.

The hydrotreated materials from reactors 30, 32 and 34 are removed via lines 36, 38 and 40, respectively, and passed to fractionators 42, 44 and 46, respectively, wherein each of the hydrotreated materials is fractionated to separate lubricating oil boiling range product from lower boiling materials.

In fractionator 42, the hydrotreated material is separated into furnace oil and lighter materials boiling below 650F., which fraction is removed overhead via line 48, and a bottoms lubricating oil product fraction, such as, a light neutral base oil, which fraction is removed via line 50. Similarly, in fractionator 44, the hydrotreated material is separated into lighter fraction removed overhead via line 52 and a bottoms lubricating base oil product such as a heavy neutral oil, which fraction is removed via line 54. Again, in fractionator 46, the hydrotreated material is separated into a lighter fraction, which is removed overhead via line 56, and a bottoms lubricating oil base stock product such as a bright stock, which is removed via line 58. The lubricating base oil products of lines 50, 54 and 58 are removed from the system for use individually as base oils or for blending operations.

FIG. 2 shows a schematic diagram illustrating employment of so-called blocked operation rather than the parallel operation of FIG. 1. In FIG. 2, four separate crude lubricating oil fractions are employed. A light distillate fraction boiling in the range from about 650 to 750F. is introduced via line 110 containing valve 112. A medium distillate fraction boiling in the range from about 750 to 850F. is introduced via line 114 containing valve 116. A heavy distillate fraction boiling in the range from about 850 to 950F. is introduced via line 118 containing valve 120 while a deasphalted oil boiling 950F.+ is introduced via line 122 containing valve 124. Each of the lines 110, 114, 118 and 122 are connected to a manifold 126 having a single inlet line 128.

In operation, three of the valves 112, 116, 120 and 124 are maintained in the closed position while one of such valves is maintained in the open position thereby permitting introduction of but one of the four crude lubricating oils into manifold 126 and from thence into reactor 130 via inlet line 128. Thus, for example, by maintaining valve 112 in the open position and valves 116, 120 and 124 in the closed position, the light distillate crude lubricating oil fraction of line 110 is passed via manifold 126 and inlet line 128 into line 130.

In reactor 130, the particular crude lubricating oil fraction being charged at the particular time is contacted with hydrogen and a suitable hydrotreating catalyst, such as, for example, a nickel-tungsten-fluorine catalyst supported on an alumina carrier having an A1 of about 18. The material hydrotreated in reactor 130 is removed therefrom and passed via line 132 to fractionator 134 wherein the hydrotreated material is separated into a light fraction and the desired lubricating oil boiling range product fraction. The fraction boiling below the lubricating oil boiling range is taken overhead from fractionator 134 by means of line 136 and removed from the system. The desired lubricating oil fraction is removed from the bottom of fractionator 134 by means of line 138 and passed to product recovery means (not shown).

As can be seen, each of the crude lubricating oil fractions of line 110, 114, 118 and 122 can in turn be treated separately in reactor 130 simply by opening the valve in the appropriate line and closing the valve in the remaining lines. Thus, to shift from treatment of the light distillate crude lubricating oil of line 110 to treatment of the medium distillate crude lubricating oil fraction of line 114 it is merely necessary to close valve 1 12 in line 110 and open valve 116 in line 114.

Reference is now made to the following examples in order to illustrate our invention is more detail.

EXAMPLE 1 In this example, the crude lubricating oil charge stocks employed were a deasphalted oil (DAO) obtained from a residual fraction, a heavy distillate fraction, a medium distillate fraction and an aliquot blend of these three fractions. Each of these four crude lubricating oil charge stocks was separately subjected to hydrotreating employing an average catalyst bed temperature of 735F., a pressure of 3,000 psig and a liquid hourly space velocity of 1.0. The hydrogen feed rate employed in the several runs varied over a range from about 4,800 to about 5,100 standard cubic feet per barrel of charge stock. The catalyst employed in all four hydrotreating operations was a nickel-tungstenfluorine on silica-alumina carrier, which carrier had an activity index of about 75.

The following Table I shows the boiling ranges of the three fractions and the aliquot blend employed as feedstocks and the hydrogen consumption and yield data (30 X vol.% of 625F.+ based on C effluent) After hydrotreating, the liquid effluent from hydrotreating each of the three individual fractions was separately fractionated so as to remove undesired lower boiling materials and the remaining portions of the three products were combined to form a bulk product. In a similar manner, the effluent from hydrotreating the aliquot blend was also fractionated so as to remove undesired lower boiling components and to provide the desired lubricating oil product. Inspection data for the two lubricating oil products are shown in Table ll below:

TABLE II Blend of Separately Product from Hydro- I-Iydrotreated Fractions treated Aliquot Blend Viscosity, SUS

at F. 335 299 at 2l0F. 55.2 53.3 VI 104 From the above data, it will be noted that both the product from blending the separately hydrotreated and separately fractionated fractions and bulk product obtained from hydrotreating and fractionating the aliquot blend have substantially identical VIs. It will also be noted however, that the blended product has a substantially higher viscosity than the bulk product produced from the aliquot blend. This advantageous possession of a greater viscosity is particularly noticeable when comparing the viscosities of the products at 100F.

EXAMPLE 2 In this example, the deasphalted oil and the heavy distillate fraction as well as the aliquot blend employed in Example 1 were again subjected to hydrotreating employing the same operating conditions and catalyst as also employed in Example 1. In this operation, however, the effluent from hydrotreating the aliquot blend was fractionated so as to provide a bright stock product having a VI in the range of 100 to 105 and also to provide a heavy distillate lubricating oil having a VI in the range of 95 to 100. Each of the effluents from the separate hydrotreating of the DA and heavy distillate charge stock were separately fractionated so as to obtain product fractions of the same boiling range as the bright stock and heavy distillate lubricating oil products of the aliquot blend, i.e. the hydrotreated DAO was fractionated to obtain a bright stock boiling range material and the heavyd istillate effluent was fractionated to obtain the heavy distillate lubricating oil boiling range product. Thefollowing TABLE III shows boiling range and inspection data for the various product fractions obtained:

TABLE II] DAO Heavy Aliquot Distillate Blend Product Fractions Boiling Range (TBP) l050F.+ Vis, SUS at 100F. 1900 1600 SUS at 2l0F. 135 123 VI 102 104 965-1050F. Vis, SUS at 100F. 760 535 SUS at 2l0F. 77.5 66.0 Vl 98 99 Again, it will be noted from the above data that the product fractions obtained from the separate hydrotreating and fractionation of the DA0 and heavy distillate charge have substantially the same Vls as the corresponding boiling range fractions from the bulk product obtained by fractionating the hydrotreated aliquot blend. Once more, it will be seen that the l,050F.+ fraction from the separate hydrotreatment and fractionation of the DA0 has a substantially higher viscosity at both 100 and 2l0F. as compared to that of the comparable boiling range fraction obtained from the aliquot blend. The same comparison can be made between the 965 to 1,050F. product from the separate hydrotreatment and fractionation of the heavy crude lubricating oil which has a substantially higher viscosity at both and 210F. compared to the corresponding boiling range fraction obtained from the aliquot blend.

We claim:

1. An improved process for the production of lubricating oil which comprises separately subjecting a plurality of crude lubricating oil fractions to hydrotreating at a temperature from about 600 to about 900F. and a hydrogen partial pressure from about 2,000 to about 10,000 PSI, and separately subjecting the effluents from the separate hydrotreating operations to fractionation to separate desired boiling range product fractions from lower boiling effluents.

2. heavy distillate of claim 1 wherein each of the crude lubricating oil fractions, other than The following Table fraction, boils over a nominal range of about 100F. and the boiling ranges of all the crude lubricating oil fractions encompass a spectrum of at least about l50F.

3. The process of claim 1 wherein the crude lubricating oil fractions are obtained by fractionating a wide boiling crude lubricating oil.

4. The process of claim 1 wherein the hydrotreating conditions are selected so as to maintain a yield from each hydrotreating operation of at least about 50 percent by volume of hydrotreated material boiling above about 625F. based'upon charge to the hydrotreating operation, to maintain at least 22 mol per cent of the normally liquid effluent from each hydrotreating operation in the form of materials boiling above about 625F., and to maintain a hydrogen consumption, measured as standard cubic feet per barrel of charge stock, in each hydrotreating operation at less than about the product of 30 multiplied by the volume per cent of 625F.+ material in the normally liquid effluent.

5. The process of claim 1 wherein the separate fractions are conducted so that the lower boiling effluents separated from the desired boiling range product fractions comprise from about 10 percent to about 30 percent by volume of lubricating oil boiling range material based upon total lubricating oil boiling range components contained in each hydrotreating effluent.

$3 33 3 UNITED STATES PATENT omen CERTIFICATE OF CORRECTION Patent No. 7 4.518 baud October 9, 1973 Inventofls) Alfred M. Henke and Harry C. Stauffer It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 1, line 61, "The" should read -'-A--.

Column 3, line 9, "as" should read --a--.

Column 3, line 31, "finish" should read --finishing-. Column -6, line 16, "material" should read --materials--. Column 6, line 22, "highest" should read lightest--. Column 9, line 23, "heavyd" should read heavy---.

Column 9, line 23, "istillate' should read --distillate--.

Column 10, line 19, "heavy distillate" should read The process.

Column 10, line 20 & 21, "The following Table" should read a residual--.

Signed and sealed this 25th day of June 19714..

(SEAL) AtteSt:

EDWARD M.FLE'I'CHER,JR. 'c. MARSHALL DANN Attesting Officer Commissioner of Patents 

2. The process of claim 1 wherein each of the crude lubricating oil fractions, other than a residual fraction, boils over a nominal range of about 100*F. and the boiling ranges of all of the crude lubricating oil fractions encompass a spectrum of at least about 150*F.
 3. The process of claim 1 wherein the crude lubricating oil fractions are obtained by fractionating a wide boiling crude lubricating oil.
 4. The process of claim 1 wherein the hydrotreating conditions are selected so as to maintain a yield from each hydrotreating operation of at least about 50 percent by volume of hydrotreated material boiling above about 625*F. based upon charge to the hydrotreating operation, to maintain at least 22 mol per cent of the normally liquid effluent from each hydrotreating operation in the form of materials boiling above about 625*F., and to maintain a hydrogen consumption, measured as standard cubic feet per barrel of charge stock, in each hydrotreating operation at less than about the product of 30 multiplied by the volume per cent of 625*F.+ material in the normally liquid effluent.
 5. The process of claim 1 wherein the separate fractionations are conducted so that the lower boiling effluents separated from the desired boiling range product fractions comprise from about 10 percent to about 30 percent by volume of lubricating oil boiling range material based upon total lubricating oil boiling range components contained in each hydrotreating effluent. 